BMW 3 Series E90 E91 E92 E93 325d 330d M57N2 Hose Expansion Tank Return Pipe

Visual condition of the part

The product shows signs of use visible in the photos.

BMW 3 Series E90 E91 E92 E93 325d 330d M57N2 Hose Expansion Tank Return Pipe is an original cooling system component from the Lines, hoses and pipes category, designed for precise coolant routing in the BMW 3 Series E90 330d engine. This used OEM part ensures factory geometry, robust construction, and a secure fit to factory connectors and mounts, which facilitates installation and reduces the risk of leaks.

Specifications and technical data

• SKU: 7804891
• Mark: BMW (Genuine OE)
• Condition: Used
• OEM Part Number: 7804891
• Substitutable numbers: 17127804891, 7804891, 17127789591, 7789591
• Category: Hoses, Lines & Pipes

Function and application in the cooling system

The radiator hose in the BMW E90 330d is responsible for a stable connection of cooling system components and the safe flow of fluid between the radiator and the engine. A properly selected water pipe:

• maintains system tightness at high operating temperatures,
• ensures adequate rigidity and resistance to engine vibrations,
• minimizes the risk of engine overheating resulting from coolant loss.

Thanks to the preservation of the factory shape and connection diameters, this reference component allows for installation without modifications, maintaining the original hose routing in the engine bay.

Benefits of using an original BMW hose

Using an original radiator hose in the BMW E90 330d brings a number of practical benefits in daily operation:

• Factory fit – the correct length, diameters, and angle of the end profiles facilitate installation and reduce stress on the connectors.
• Stable cooling system operation – proper fluid flow helps maintain the optimal engine operating temperature, which affects its durability.
• Compatibility with original clamps and brackets – the hose works with factory mounts, which organizes the installation routing in the engine bay.
• A solution consistent with the manufacturer's design – no need to adapt universal hoses or additional connectors.

Characteristics of the component from the Lines, hoses and pipes category

Cooling system hoses in modern BMW diesel units operate under demanding temperature and pressure conditions. The water pipe used in the E90 330d has been designed to:

• maintain the flexibility necessary to compensate for engine movements relative to the body,
• resist coolant and typical operational contaminants,
• maintain tightness after multiple heating and cooling cycles.

As a result, the radiator hose from this series serves well as a service component when replacing worn or brittle hoses in the cooling system, restoring proper operating conditions for the power unit.

Condition and installation aspects

The offered water pipe is a used component, which in practice means an economical way to repair the cooling system while maintaining the manufacturer's original specifications. Before installation, it is recommended to perform a standard inspection of the connection sockets, clamps, and other hoses in the system to avoid secondary leaks.

Replacing the radiator hose in the BMW E90 330d is a typical service operation performed when:

• coolant leaks are detected in the vicinity of the hoses,
• there are visible cracks, fissures, or material deformations,
• performing preventive cooling system maintenance at higher mileages.

Expanding BMW cooling system service

If you are planning a comprehensive repair or upgrade of the cooling system area in your BMW and need other components from the same group, such as additional lines, flexible hoses, or rigid fluid pipes, check the available parts in the BMW lines, hoses and pipes category.

If you are considering a broader car upgrade and want to improve driving comfort in the interior as well, it is worth checking out the guide on replacing seats with branded parts from dismantling – you can find practical tips in the article Interior metamorphosis: how branded seats from dismantling improve comfort and car value.